1. Field of the Invention
The present invention pertains to noise suppressor for fluid systems. Specifically, it pertains to a noise suppressor suitable for suppressing noise produced by hydraulic power assemblies which supply power to hydraulic elevators.
2. Description of the Prior Art
In a hydraulic elevator, a vertical hole is normally drilled at the bottom of an elevator shaft and a hydraulic piston and cylinder unit placed therein. A rod acting as a piston is disposed in the cylinder and attached at the upper end thereof to the base of the elevator car. When fluid power is supplied to the piston and cylinder unit, the piston rod is raised, causing the elevator to rise. To lower the elevator, fluid is simply allowed to exit the piston and cylinder unit, allowing the piston rod to descend as the elevator car descends.
As a rule, the power assembly for supplying pressurized fluid to the piston and cylinder unit is mounted at some accessible location and connected to the piston and cylinder unit by a hydraulic line. The power assembly conventionally includes a fluid reservior, a hydraulic pump and a hydraulic valve for controlling fluid flow to and from the piston and cylinder unit. In addition, control apparatus is provided for controlling the operation of the pump and control valve. These items are conventionally mounted in a unitary housing so that the power assembly can be preassembled before installation to provide a compact and easily installed unit. Such a power assembly and its relationship with a hydraulic elevator is shown in my copending patent application Ser. No. 838,149.
Due to the pumping and movement of hydraulic fluids in hydraulic elevator fluid systems, a certain amount of noise is produced. While such noise may have no bearing on the operation of the overall system, it is not desirable. For this reason, most hydraulic power assemblies for operation of hydraulic elevators are provided with some sort of device for suppressing or muffling the noise created by the operation of such systems. As evidenced by the fact that there are several types of these devices, a completely satisfactory noise suppressor has not yet been developed.